They exist, but nowadays you're not really spoilt for choice. VO do some, I have an UNO aero one I use, but it's actually more practical to go for a 1 1/8" steerer with a shim and a 25.4/26mm clamp. Have you considered using a shim, or just dead set against it?
Threadless - ahead stem for 1 inch fork Wanted! 25.4 or 26mm handlebar clamp.